The rear wheels of trucks typically have a cylindrical section around which a tire is secured and a generally planar web section which is transverse to one end of the cylindrical section. The planar section has a centrally located opening for receiving the oil hub of a truck axle, and surrounding the central opening is a plurality of spaced holes for receiving a plurality of lugs mounted around the end of the axle for retaining the wheel. The oil hub at the end of the axle extends through the central opening of the wheel and is readily visible from the exterior thereof.
To improve the appearance of the central portion of such truck wheels, a cover having a cylindrical section with a transverse outer end can be fitted over the oil hub with the cylindrical section of the cover fitted around the sides of the oil hub. Such covers have previously been attached by an exterior flange at the wheel end thereof which has a plurality of spaced holes positioned such that they can be aligned with the threaded studs used to retain the wheel to the hub. The cover is retained by the lug nuts which retain the wheel to the axle.
The laws of certain states require that trucks travelling across the roads of the state be stopped and the wheels thereof inspected for, among other things, cracks in the web portion of the wheels. When portions of such wheels are covered by a wheel cover having an exterior flange and retained by the lug nuts which retain the wheel, the web portion of the wheel near the central opening, and surrounding the retaining studs cannot be inspected without first removing the decorative cover. However, to properly attach a wheel of a truck, the lug nuts must be tightened with a great amount of torque and cannot be loosened without proper tools which are not available on the open road. A truck fitted with an oil hub cover having an exterior flange must, therefore, be routed off the road to a suitable service station in order that the required inspection be made.
It would be desirable to provide an oil hub cover for a truck wheel which can be securely attached to a truck axle without requiring an exterior flange attached to the studs of the axle such that truck's wheels fitted with the cover can be inspected without requiring removal of the lug nuts.